I will have a longer post dealing with the larger issues raised in this monograph, but for now let me draw your attention to this snippet below on magazines. I have been slowly going over my cached mags, replacing black followers with green and swapping GI springs for Wolff. As I do, I inspect the mag bodies for problems, throwing any with dings, cracks or bulges into the trash along with the black followers. If I had the money, I would buy all P-Mags for the girls' M-4geries, but I don't, so I continue to upgrade the mags I have as I can afford it. Although, Midway (if I recall correctly) recently ran a sale on Type One's for $10 each if you bought ten. That's hard to beat.
Anyway, here is MAJ Ehrhart on the subject of magazines.
Standard USGI-issue M-16/M-4 magazine.
The magazine is an important part of the rifle. When originally designed by Eugene Stoner, the magazine was meant to be a lightweight, disposable item. Due to this concept, the magazine was made from aluminum and not designed to be durable. Soldiers soon learned that the magazine was not disposable and that care was required to keep the weapon reliable.
There are several things that soldiers can do to ensure their magazines work. The most important thing to do is to keep them clean. Just as sand can find its way into the rifle, it will find its way into the magazines. Magazines should frequently be disassembled and brushed clean. Pulling a cleaning rag through the body several times is adequate. Inspect the back of the feed lips to ensure they are not cracked and the lips have not spread apart. Load about 15 cartridges into the magazine and while holding it in one hand, smack the base of the magazine with the other. If several rounds pop out, either the feed lips are spread and/or the magazine has a weak spring. The entire magazine should be discarded. Soldiers can identify potential problems in magazines by numbering each magazine with a paint marker and noting any malfunctions caused when the magazine is used in the weapon.
MagPul P-Mag Type One magazines, with inspection window.
Several upgrades are available to increase the reliability of the issued magazines. A company called Magpul makes the best upgrades the author has used. Their original product consisted of a slip-on rubber ring for the bottom of the magazine. It made it easier to grasp your magazines from your ammunition pouches but also protected the delicate floor plate tabs, which have a tendency to break after extended use. They also designed a new, anti-tilt follower that greatly increases feeding reliability of the standard issue magazine. In 2007, the company came out with their own version of a magazine for the M16/M4 known as the PMAG. Constructed of resilient polymer, the magazine is nearly indestructible. (Figure 8) When the polymer cracks or breaks, it is easily recognizable, unlike with the standard issue magazines. These magazines represent the cutting edge of technology for making the rifle more reliable. Recently, the PMAG was assigned a national stock number, so units can now order these magazines through the supply system. 87 All combat arms units should consider replacing their standard issue magazines with the much more reliable PMAG.
P-Mag Type II, Solid Body.
Magpul PMAG NSN's are 1005015765159 for a black magazine and 1005015765164 for a black magazine with a narrow translucent window on both sides of the magazine with witness marks for 5, 15, and 25 rounds. -- Increasing Small Arms Lethality in Afghanistan: Taking Back the Infantry Half-Kilometer, MAJ Thomas P. Ehrhart, USA, pp. 43-44.